The man, identified only as Mr Kim, checked into a motel in Incheon City near Seoul with his girlfriend in April 2010 after buying two live octopuses from a local restaurant.

He later called reception to say his girlfriend, identified by her surname Yoon, had collapsed and stopped breathing after eating one of them. She was taken to hospital but died 16 days later. Yoon's family cremated her body, reported South Korea media.

Police initially saw the case as an accident and closed the file. 

But they were forced to reopen the case five months later after a TV programme highlighted efforts by Yoon’s father to have Kim investigated, after discovering his daughter had taken out a life insurance policy just before she died.

The boyfriend was the sole policy beneficiary and collected 200 million won (HK$1.4m).

Kim was subsequently convicted of murder in October and sentenced to life imprisonment by a court that cited, “compelling indirect evidence” he suffocated Yoon for the insurance money.

Kim appealed and the conviction was overturned by a higher court in April, after which prosecutors took the case to the Supreme Court.

Live octopus is a delicacy in South Korea but is known to be a hazard that can cause choking, since the still-moving suction cups can cause pieces of tentacle to stick in a person’s throat.

A baby octopus is often consumed whole, while larger varieties are cut up and the still-wriggling tentacles eaten with a splash of sesame oil.

A tentacle was found in Yoon’s throat and both her family and police had initially accepted Kim’s story that she accidentally choked to death.